共查询到16条相似文献,搜索用时 54 毫秒
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利用扫描电子显微镜、拉曼散射光谱和光致发光谱对在SiC衬底上采用MOCVD异质外延的GaN:Mg薄膜特性进行研究发现:除了一部分Mg原子替代Ga原子呈现受主性外,大部分Mg原子以间隙原子状态(Mgi)存在,并且在缺陷或者位错处大量聚集引起薄膜张力应力减小,薄膜在降温过程中由于应力不均匀会在部分区域内出现大量的裂纹;Mg的掺杂会加剧GaN无序化程度,致使薄膜质量变差;而室温下的PL谱测量表明蓝带发光由DAP(深施主—浅受主)复合引起,其中D为MgGaVN
关键词:
GaN∶Mg
异质外延
扫描电子显微镜
拉曼散射
光致发光谱 相似文献
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用金属有机物化学气相沉积技术在蓝宝石衬底上外延了高P组分的GaN1-xPx 薄膜.利用x射线衍射仪和拉曼光谱仪研究了P对GaN1-xPx晶体结构的影响.研究结果表明:随着P组分比的增加,GaN1-xPx(0002)衍射峰逐渐向小角度移动,即晶格常数变大;与非掺杂GaN相比,GaN1-xPx薄膜的拉曼光谱中出现了4个新的振动模式,将它们分别归因于P族团引起的准局部振动模式、Ga-P键振动引起的间隙模,以及来自缺陷引起的无序激活散射.同时,随着P组分比的增加,A1(LO)模式的频率向低频方向移动,这种红移现象起因于合金化和应变的影响. 相似文献
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通过热氧化氟化锌(ZnF2)薄膜的方法制备出氟掺杂的多晶ZnO薄膜,ZnF2薄膜是利用电子束蒸发方法沉积在Si(100)衬底得到的。利用X射线衍射和X射线电子能谱研究了ZnF2薄膜向ZnO的转变过程。实验结果表明,在400℃退火30min的条件下能够获得六方纤锌矿结构的ZnO:F薄膜。对ZnO:F薄膜的室温光致发光谱可以观察到位于379nm、半峰全宽为73meV的紫外发射峰,而相应于缺陷的深能级发射则完全猝灭。表明ZnO中残留的F能够有效地增强激子的发光,同时使缺陷发光强度明显降低。对F掺杂对ZnO的发光性能的影响进行了讨论。 相似文献
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InAlN/AlN/GaN异质结中,名义上的AlN插入层实为Ga含量很高的AlGaN层, Al, Ga摩尔百分比决定了电子波函数与隧穿几率,因此影响与InAlN/AlGaN势垒层有关的散射机制.本文通过求解薛定谔-泊松方程与输运方程,研究了AlGaN层Al摩尔百分含量对InAlN组分不均匀导致的子带能级波动散射、导带波动散射以及合金无序散射三种散射机制的影响.结果显示:当Al含量由0增大到1,子带能级波动散射强度与合金无序散射强度先增大后减小,导带波动散射强度单调减小;在Al含量为0.1附近的小组分范围内,合金无序散射是限制迁移率的主要散射机制,该组分范围之外,子带能级波动散射是限制迁移率的主要散射机制;当Al摩尔百分含量超过0.52,三种散射机制共同限制的迁移率超过无插入层结构的迁移率, AlGaN层显示出对迁移率的提升作用. 相似文献
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采用分子束外延技术(MBE)在MgO(001)基板上沉积了氧化铬薄膜,并利用x射线衍射 (XRD)和x射线反射谱(XRR)对薄膜的晶体结构进行了表征.θ—2θ扫描和倒易空间图(R SM)揭示出薄膜为单相c轴外延生长,晶体结构为体心正交,晶胞常数a,b,c分别为0.8940±0.0003,0.298±0.0002和0.3897±0.0002nm.扫描表明薄膜在面内具有90°孪晶,取向关系为a∥MgO〈110〉,c∥MgO(001).XRR谱测得薄膜的电子 密度为1350±20nm-3,与由晶胞体积 计算得
关键词:
一氧化铬薄膜
x射线衍射
倒易空间图
x射线反射谱 相似文献
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用金属有机物化学气相沉积技术在蓝宝石衬底上外延了高P组分的GaN1-xP x 薄膜.利用x射线衍射仪和拉曼光谱仪研究了P对GaN1-xPx晶体结构 的影响.研究结果表明:随着P组分比的增加,GaN1-xPx(0002)衍射 峰逐渐向小角度移动,即晶格常数变大;与非掺杂GaN相比,GaN1-xPx薄 膜的拉曼光谱中出现了4个新的振动模
关键词:
1-xPx')" href="#">GaN1-xPx
金属有机物化学气相沉积
x射线衍射
拉曼光谱 相似文献
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Xu Pan Xiaoliang Wang Hongling Xiao Cuimei Wang Cuibai Yang Wei LiWeiying Wang Peng JinZhanguo Wang 《Applied Surface Science》2011,257(20):8718-8721
Al0.91Ga0.09N epilayers have been obtained by pulsed atomic layer epitaxy (PALE) technique on sapphire (0 0 0 1) substrates. Deep ultraviolet (DUV) photoluminescence (PL) spectroscopy and Raman scattering spectrum have been employed to study the optical transitions in Al0.91Ga0.09N epilayers. We found the exciton-phonon interaction by fitting the asymmetric PL peak, in which the transverse optical phonon (TO) and the longitudinal optical (LO) phonon are the main contributor. The abnormal S-shaped temperature dependence of the PL band peak is less pronounced or has disappeared. Further analysis shows that there possibly exists a high density of deeper localized state (∼90 meV) in Al0.91Ga0.09N. The formation of these localized states provides a favorable condition for efficient light emission. 相似文献
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采用有机金属化学气相沉积(MOCVD)在r面蓝宝石衬底上生长a-AlGaN外延膜,研究了AlN插入层对a-AlGaN外延膜的应力和光学性质的影响。根据高分辨X射线衍射(HRXRD)技术和扫描电子显微镜(SEM)我们可以得到,AlN插入层有效地提高了a-AlGaN外延膜的晶体质量并减小了外延膜材料结构的各向异性。由拉曼光谱得到AlN插入层的引入减小了a-AlGaN外延膜的面内压应力,其原因是AlN插入层可以当作衬底有效的调制与减小a-AlGaN外延膜与r面蓝宝石衬底的晶格失配,从而使a-AlGaN的面内应力得到适当释放。对室温下的光致发光进行测量得到AlN插入层的使用使近带边发射峰(NBE)发生了红移,这可能是由于残余应力的减小引起。 相似文献
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Effect of Si doping in wells of AlGaN/GaN superlattice on the characteristics of epitaxial layer 下载免费PDF全文
An AlGaN/GaN superlattice grown on the top of a GaN buffer induces the broadening of the full width at half maximum of (102) and (002) X-ray diffraction rocking curves. With an increase in the Si-doped concentration in the GaN wells, the full width at half maximum of the (102) rocking curves decreases, while that of the (002) rocking curves increases. A significant increase of the full width at the half maximum of the (002) rocking curves when the doping concentration reaches 2.5 × 1019 cm-3 indicates the substantial increase of the inclined threading dislocation. High level doping in the AlGaN/GaN superlattice can greatly reduce the biaxial stress and optimize the surface roughness of the structures grown on the top of it. 相似文献
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The polarized Raman spectroscopy is capable of giving confirmation regarding the crystalline phase as well as the crystallographic orientation of the sample. In this context, apart from crystallographic X‐ray and electron diffraction tools, polarized Raman spectroscopy and corresponding spectral imaging can be a promising crystallographic tool for determining both crystalline phase and orientation. Sub‐micron sized hexagonal AlGaN crystallites are grown by a simple atmospheric pressure chemical vapor deposition technique using the self catalytic vapor–solid process under N‐rich condition. The crystallites are used for the polarized Raman spectra in different crystalline orientations along with spectral imaging studies. The results obtained from the polarized Raman spectral studies show single crystalline nature of sub‐micron sized hexagonal AlGaN crystallites. Optical properties of the crystallites for different crystalline orientations are also studied using polarized photoluminescence measurements. The influence of internal crystal field to the photoluminescence spectra is proposed to explain the distinctive observation of splitting of emission intensity reported, for the first time, in case of c‐plane oriented single crystalline AlGaN crystallite as compared with that of m‐plane oriented crystallite. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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Sol-gel derived Mg doped tin oxide (Sn1−xMgxO2) nanocrystals were synthesized with x ranging between 0.5 and 7 at. %. Characteristic single phase tetragonal structure of pure and doped samples was obtained and doping saturation was inferred by X-ray diffraction analysis. Structural, morphological and phase informations were obtained by high resolution transmission electron microscope, field emission scanning electron microscope and X-ray photoelectron spectroscopy respectively whereas bonding information was obtained from Fourier transformed infrared spectroscopy. Measurement of different electrical parameters with frequency (200 Hz-105 Hz) has been carried out at room temperature. Ultrahigh dielectric constant and metallic AC conductivity were observed for undoped tin oxide and the profiles reflected highly sensitive changes in the atomic and interfacial polarizability generated by doping concentrations. Relaxation spectra of tangent loss of any sample did not show any loss peak within the frequency range. Both the grain and grain boundary contributions are observed to increase as the doping concentration increased. Results of first principle calculation based on density functional theory indicated effective Fermi level (EF) suppression due to Mg doping which is responsible for the experimentally observed conductivity variation. AC conductivity was found to depend strongly on the doping concentration and the defect chemistry of the compound. Mg doped SnO2 may find applications as a low loss dielectric and high density energy storage material. 相似文献
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Influence of Schottky drain contacts on the strained AlGaN barrier layer of AlGaN/AlN/GaN heterostructure field-effect transistors 下载免费PDF全文
Rectangular Schottky drain AlGaN/AlN/GaN heterostructure field-effect transistors (HFETs) with different gate contact areas and conventional AlGaN/AlN/GaN HFETs as control were both fabricated with same size. It was found there is a significant difference between Schottky drain AlGaN/AlN/GaN HFETs and the control group both in drain series resistance and in two-dimensional electron gas (2DEG) electron mobility in the gate-drain channel. We attribute this to the different influence of Ohmic drain contacts and Schottky drain contacts on the strained AlGaN barrier layer. For conventional AlGaN/AlN/GaN HFETs, annealing drain Ohmic contacts gives rise to a strain variation in the AlGaN barrier layer between the gate contacts and the drain contacts, and results in strong polarization Coulomb field scattering in this region. In Schottky drain AlGaN/AlN/GaN HFETs, the strain in the AlGaN barrier layer is distributed more regularly. 相似文献